Polymerization of alpha-monoolefins in the presence of titanium trichloride, organometallic reducing agent comprising zinc dihydrocarbyl, and an organic amine



United States Patent POLYMERIZATION 0F ALPHA-MONOOLEFINS IN THE PRESENCEOF TITANIUM TRICHLORIDE, ORGANOMETALLIC REDUCING AGENT COM- PRISING ZINCDHIYDROCARBYL, AND AN 0R- GANIC AMINE I John Boor, In, El Cerrito,Calif., assignor to Shell Oil Company, New York, N.Y., a corporation ofDelaware No Drawing. Filed July 22, 196 4, Ser. No. 384,529 17 Claims.(Cl. zen-93.7

This application is a continuation-in-part of copending applicationSerial No. 833,949 filed August 17, 1959, and now Patent No. 3,155,626.

This invention relates to the polymerization of unsaturatedhydrocarbons. More particularly, it relates to improvements in catalystsfor the low pressure polymerization of alpha-monoolefins and their useto obtain polymers of high crystallinity and controlled molecularweight.

It is known that alpha-monoolefins can be polymerized at lowtemperatures and low pressures to produce polymers which are linear instructure. The methods for carrying out such polymerizations aregenerically referred to as low pressure methods and the polymers thusproduced are termed low pressure polyolefins. They are generally linear,isotactic and crystalline. Low pressure polymers are produced byemploying any of a variety of catalysts which are called low pressure orZiegler type catalysts. The use of catalysts of this type for thepolymerization of diolefins has also been suggested.

A particularly useful linear polymer of the low pressure type ispropylene. Isotactic polypropylene is highly useful because it hasimproved physical properties such as higher tensile strength, highermelting point and the like as compared to amorphous polypropylene.

The measurement generally employed as an indication of molecular weightof these polymers is the intrinsic viscosity (IV) expressed indeciliters per gram (dl./g.). The intrinsic viscosity of polypropyleneproduced by known catalyst systems is usually in the range of 4 to 20dl./ g. determined in decalin at 150 C. For many uses, e.g., for theproduction of molded products of polypropylene, it is desirable to haveIV values in the range of 2 to 4 dl./ g.

The degree of isotacticity of polymers is indicated by the percentage ofpolymer insoluble in a hydrocarbon solvent under standard conditions,e.g., in boiling heptane. In the production of polypropylene with knowncatalyst systems the percent insolubles values may be as low as 40 or50% or as high as 98 or 99%. In gen eral, the polymers ofalpha-monoolefins have better overall properties when the crystallinityis high. High crystallinity is found in high isotactic polymers. In theproduction of polypropylene, for example, a crystallinity equivalent to90 to 95% or more insoluble in heptane is desired. Only a few of thesuggested low pressure catalyst systems produce polyolefins having thedesired high degree of crystallinity.

It has been found that systems that produce a highly linear polymergenerally cause the molecular weight of the polymer to be too high forefiicient molding, as indicated by an excessively high intrinsicviscosity. Attempts have been made to produce polymers of lowerintrinsic viscosity by the use of various additives together with thecatalyst. This has met with only partial success because the use of manyadditives, while resulting in a polymer of lower intrinsic viscosity, atthe same time reduces the crystallinity of the resulting polymer. suchother physical properties as tensile strength, melt index, yield point,stress and the like may be adversely afiected.

The present invention is concerned with an improvement in the lowpressure polymerization of alpha-monoolefins which permits theproduction of polyolefins of desirably low intrinsic viscosity without aconcomitant loss of degree of crystallinity or other desirableproperties.

It is an object of this invention to provide improved low pressurepolymerization catalysts. Another object is to provide an improvedmethod for the polymerization of alpha-monoolefins. A further object isto provide a method for catalyzing the polymerization ofalpha-monoolefins of three or more carbon atoms per molecule wherebypolymer of controlled molecular weight can be obtained withoutdecreasing the crystallinity of the resulting polymer as molecularweight is decreased. Other objects will become apparent as thedescription of the invention proceeds.

These and other objects are accomplished in the process for thepolymerization of ethylenically unsaturated compounds with astereospecific low pressure polymeriza tion catalyst of the Zieglertype, such as a catalyst formed by mixing an organometallic reducingagent with a compound selected from the group consisting of compounds oftransition metals selected from Groups IVa, Va, VIa and VIII of theMendeleev Periodic Table and manganese, by the improvement comprisingconducting the polymerization in the presence of a zinc dihydrocarbylwhich is present as said reducing agent or as an adjunct of saidreducing agent, together with a controlled amount of an amine selectedfrom certain groups defined in further detail below.

Zinc dihydrocarbyls are known compounds. They are described, forexample, in The Chemistry of Organometallic Compounds by E. G. Rochow etal., John Wiley and Sons, 1957, pages -105; Table 5 of the reference, atpage 102, lists physical characteristics of zinc alkyls and zinc aryls.

Reactants, catalysts and conditions useful in the process of thisinvention are known in the prior art on the production of linearpolymers of alpha-monoolefins. They are described, for example, inBelgian Patents Nos. 534,792 and 538,782 to Ziegler and Ziegler et al.,respectively. In general, low pressure catalysts are said to include thereaction product of a compound of a Group IV to V1 or VIII transitionmetal and a strong reducing agent.

The catalysts for use in this invention comprise the reaction product of(1) a compound, preferably a halide, and more preferably a halide in areduced valence state, of a transition metal selected from the metals insubgroups a of Groups IV and V of the Mendeleev Periodic Table (asillustrated on page 28 of Ephraim, Inorganic Chemistry, Sixth EnglishEdition) with (2) an organometallic reducing compound which may be, forexample, aluminum trialkyl or zinc alkyl or a compound of the formula RR AlX wherein R and R are hydrocarbon groups and X is halogen.

Particularly preferred catalysts are those selected Also,

from the reaction product of a trihalide of a Group IVa metal such aszirconium trichloride, titanium trichloride and the like and an aluminumdialkyl halide or aluminum trialkyl or mixtures thereof. Representativealuminum alkyls include, for example, aluminum diethyl chloride,aluminum diethyl bromide, aluminum diisopropyl chloride, aluminumtriethyl, aluminum triisobutyl, aluminum triisopropyl and others whereinthe alkyl radicals have from 1 to 10 carbon atoms.

Although many catalyst compositions have been suggested and may beemployed to produce low pressure polymer, in practice it is found thatmany of these compositions produce only small amounts of polymer underpractical conditions or produce polymers which are un desirable for mostpurposes by reason of having, for example excessively high molecularweight or excessive amounts of very low molecular weight material orhaving an undesirably low degree of crystallinity and the like. Only fewcatalysts systems actually are adapted to produce on a commercial scalepolymers having the required degree of stereospecificity, IV, meltindex, yield point and other properties.

It has been found that when zinc dihydrocarbyl compounds are used asadjuncts of aluminum alkyl compounds in low pressure polymerization withthe abovementioned catalysts the intrinsic viscosity of the resultingproduct can be substantially reduced, down to a desirable range. It hasalso been found that when zinc dihydrocarbyl is used as the solereducing agent together with a transition metal of the above-describedtype the resulting polymer has a desirably low intrinsic viscosity.However, the use of zinc dihydrocarbyl in the polymerization of alphaolefins of three or more carbon atoms per molecule generally reducesintrinsic viscosity at the cost of some loss in crystallinity of theresulting polymer.

It has now been found that the loss of crystallinity resulting from useof zinc dihydrocarbyls in low pressure catalyst systems can besubstantially prevented by employing with the zinc dihydrocarbyl acontrolled amount of certain amines. The suitable amines will be furtherdescribed below. It has been found that not all amines are effectivewhen used together with zinc dihydrocarbyl and, in fact, some result incompletely deactivating the effective catalyst when used in theconcentrations which are desirable for effective amines. It is ofparticular interest in this connection that unsubstituted N-heterocyclicamines, which have been found useful with certain low pressurepolymerization catalysts, are ineffective and particularly undesirablein conjunction with zinc dihydrocarbyls.

It may be possible to explain theoretically the fact that some aminesare more effective than others when used in conjunction with zincdialkyls. The invention will, however, be described by enumerating thosealkyl amines which have been found and are believed to be effective foruse in the present invention and will be further illustrated by showingthose which have been found to be ineffective and undesirable and are tobe avoided.

The suitable amines consist of the following groups: (1) aliphatictertiary amines having at least carbon atoms per molecule and preferablyhaving from 5 to 20 carbon atoms per molecule; (2) aliphatic secondaryamines having at least 5 carbon atoms per molecule and preferably havingfrom 5 to 20 carbon atoms per molecule; (3) aliphatic primary amineshaving at least 4 carbon atoms per molecule and preferably having from 4to 20 carbon atoms per molecule; and (4) heterocyclic nitrogentcompounds having fiveor six-membered rings and having an alkyl radicalsubstituent on one or both carbon atoms alpha to a nitrogen atom in thering, the alkyl radi- Cals having a total of up to 6 carbon atoms each.

Among the secondary and tertiary aliphatic amines, all alkyl groups areusually identical but those secondary amines having two different alkylgroups and those tertiary amines having two or three different alkylgroups present are equally suitable. branched or unbranched.

Among the heterocyclic nitrogen compounds the essential configuration isa fiveor six-memebred ring containing at least one nitrogen atom andhaving an alkyl substitutent group alpha to the nitrogen atom. Typicalare, for example, alpha-alkyl-pyrrole, alpha-alkyl-pyridine,alpha-alkyl-pyrazine, alkyl sym triazine, alphaalkyl-quinoline, alphaalkyl isoquinoline, alpha-alkylnaphthyridine as well as alpha-alphasubstituted compounds such as alpha-alpha-dialkyl pyridine, pyrazine,isoquinoline or the like. The alkyl groups may have from 1 to 6 carbonatoms each. Methyl and ethyl substitutents are particularly suitable.

Although it has been generally recognized in the art that zinc alkylsshould be suitable as reducing agents for use with compounds oftransisition metals of Groups IV to VI, it is only in a few rareinstances that working examples of the use of zinc alkyls are shown inany of the patents and literature articles dealing with this sub ject,as contrasted with hundreds of examples showing the use of aluminumalkyls. Such examples as exist generally deal with the production ofpolyethylene, which does not present the problems encountered in theproduction of isotactic polypropylene or higher isotactic polyolefins.

It has been found that polymerization methods utiliz ing catalysts inwhich zinc dihydrocarbyl is the sole reducing agent are extremelysensitive to trace impurities present in the zinc dihydrocarbyl and thatvery erratic results may be produced unless a zine dihydrocarbyl of veryhigh purity is employed. A suitable technique for producing such purezinc dihydrocarbyl consists essentially of contacting technical gradezinc dihydrocarbyl with a strong reducing metal and recovering thepurified dialkyl. Preferably the purification consists of refluxing oversodium metal or barium metal or similar alkali or alkaline earth metaland subsequently distilling off the purified zinc dihydrocarbyl.Although zinc dihydrocarbyl may be employed without such elaboratepretreatment and result in satisfactory polymerization when used insmall concentrations as an adjunct of an aluminum alkyl reducing agent,it is preferable to employ in the process of this invention highlypurified zinc dihydrocarbyl.

Suitable zinc compounds for use in this invention are those having from1 to 10 carbon atoms in each hydrocarbyl group. Usually the twohydrocarbyl groups are identical but they may be different, if desired.Zinc diethyl and zinc di-n-propyl are particularly preferred compounds.Other zinc dihydrocarbyls which can be used in this invention are zincdiisopropyl, zinc diisobutyl, zinc diisoamyl, zinc diphenyl, zincditolyl and the like.

The transition metal compounds which are most particularly adapted foruse with a strong reducing agent including at least some zincdihydrocarbyl, in accordance with this invention, are various forms oftitanium trichloride. One form is the commercially availabletrichloride, which is usually a compound of purple color. In anothersuitable form, a titanium trichloride may be prepared, for example, byreacting a hydrocarbon solution of aluminum triethyl and titaniumtetrachloride in a mole ratio ranging from about 0.121 to less than0.421 at elevated temperatures until the aluminum triethyl is completelyoxidized and thereafter reacting the total product of the first stepwith a hydrocarbon solution of a suitable aluminum alkyl compound, e.g.,aluminum diethyl chloride or aliuminum triethyl to give a total aluminumto titanium mol ratio of at least 1:1. The resulting product, is asuspension of a catalyst, usually of brown, black or purple color, in ahydrocarbon solution. If desired, the; solid catalyst may be recoveredand purified by decanting; or filtration and evaporation of remainingliquid constitu-. ents. The catalyst is combined with an organometallic;reducing agent which may consist of Zing diethyl or of;

The alkyl groups may be an aluminum alkyl containing some zinc diethyl,as has been described above. When the presence of some aluminum alkyl ispermissible, the titanium compound need not be recovered as a solid butmay be used in the original suspension. The preparation of aparticularly preferred titanium trichloride catalyst in which titaniumtetrachloride is first reacted with the above-defined amount of aluminumtriethyl and subsequently with the abovedefined amount of aluminumdiethyl chloride is described in greater detail in US. Patent 2,971,925to Winkler et al. The preferred form of titanium trichloride is oftenreferred to as gamma titanium trichloride.

In a preferred mode of carrying out the present invention a catalystsolution is prepared as in said'Winkler et al. patent and to thatsolution is added an amount in the range from 0.001 to 0.5 mol of zincdihyrocarbyl per mol aluminum alkyl and an amount in the range from from0.001 to 2.0 mol of a suitable amine per mol of zinc hydrocarbyl.

In the process and catalyst according to this invention the ratio ofmetal-organic compound to TiC1 in the effective catalyst is generally inthe range from 1:1 to 10:1 and preferably in the range from 2:1 to 6: 1.Higher ratios, e.g., up to 30:1, may be employed but are generally of noadvantage. amine of the enumerated group added to the catalyst is in therange from 0.001 to 2.0 mol of amine per mol of zinc dihydrocarbyl.Although very small ,amounts .of amine, e.g., 0.001 mol per mol of zincdihydrocarbyl cause some improvement in the effectiveness of thecatalyst it is much preferred to employ amounts of amine in the rangefrom 0.5 to 1.0 mol based on zinc dihydrocarbyl. In general,lowerproportions of zinc dihydrocarbyl and of amine are required in largescale runs to obtain a. desired intrinsicyiscositylthan in small scaleruns.

The low pressure polymerizations of alpha-monoolefins, e.g., ofethylene,.propylene, butene-l, mixtures thereof and the. like arecarried. out at temperatures ranging from C. to about 120C. withtemperatures in the order of about 20 C. to 80 C..being particularlyuseful. Suit- .ablepressuresrange from about atmospheric pressure up toseveral atmospheres, withpressures in excess of 500 Preferably thecatalyst components are mixed-as solutions-in inert diluents such asheptane,

isooctane,.benzene.or the like and the.process itself-is also preferablyconducted in the presence of such inert diluents. The diluents as wellas the catalyst components and reactants are preferably pre-treated toremove harmfulimpuritiessuch 'as' sulfur, oxygen, moisture,oxygencontaining compounds and the like and the polymerization ispreferably-conducted under conditions that exclude atmospheric.impurities such as moisture, oxygen and the like. After thepolymerizationis complete the polymer is recovered by any of severalconventional means, the most common of which includes destroying thecatalyst with a compound that reacts with and inactivates the catalyst.Such compounds include, for example, low alcohols such as methanol,ketones such as acetone and the like. Thereafter, the polymerisseparated from the diluent and is washed a few times. and dried. Thepolymer produced by the.present inventiontmay be treated by anyconventional means to remove or reduce the catalyst. residues whichremain in the polymer at the termination of. the polymerization.

The invention described herein is particularly important as it relatesto the low pressure polymerization of propylene and higheralpha-monoolefins to produce polymers of high stereospecificity. Ingeneral, straight chain and branched aliphatic terminally unsaturatedolefins having from 3 to 20 carbon atoms per molecule and preferablyfrom 3 to 12 carbon atoms per molecule are the most suitable feeds. Thisincludes l-butene, l-pentene, 3-methyl-1- The :amount of an effective.

;pentene l-decene-and the like. The present improvements may, however,also be utilized in the polymerization of ethylene or mixtures ofethylene and propylene and other ethylenically unsaturated compounds aswell as those diolefins which can be polymerizedlby low pressurecatalysts. The numerous teachings of the prior art with respect toZiegler type polymerization techniques, proportions of catalyticcomponents and the like are applicable in the process of this invention.

"The following will be further illustrated by,means,0f the followingexamples which, however, are only for the purpose of further explanationand are not to be considered a limitation of the invention. In theseexamples the crystallinity of the polypropylene. produced was determinedby. measuring the percent of the product which was insolublein boilingheptane. The higher this value, the more crystalline the polymer.

Example 1 This example illustrates a typical procedure 'for'thepolymerization of propylene by a conventional low pressure processwherein an additive of the type of the present invention is notemployed.

Fifty ml. ofpurified heptane is placed' intothe body of a .100 ml.agitated autoclave previously flushed with purified nitrogen. ,Nitrogenis bubbledthrough the heptaneand metal alkyl is added to the solventwith a syringe. A weighed sample of TiCl previously purified byevacuation at 250 C., is added to the solventfrom a vial. The uppersection of the autoclave is flushed with nitrogen and the two autoclaveparts are joined while nitrogen is passed into both. The autoclave ispressured and flushed with nitrogen five times at 200 p.s.i.g. Theautoclave is then heated to the temperature of polymerization (70 C.)and. purified propylene is added as a gas with agitation. The pressureis maintained at to p.s.i.g.

In this instance the..metalxalkyl added is 0.34 gram of zinc diethyl andthe amount of titanium trichloride added is 0.15 gram.

At the termination of the polymerization the temperature is lowered toabout room temperature and solid polypropylene is recovered bydeactivating the catalyst, recovering the polymer and washing it. Thereis obtained a total of 28.9 grams of polypropylene, 77% of which isinsoluble in boiling heptane.

Example '2 The procedure of Example 1 is repeated in every respectexcept that 0.1 millimole of monoethyl amine is added to the reactorafter the catalyst components are charged. In this case there isrecovered a total of 0.3 gram of polymer. This is too little to permitsignificant evaluation of its crystallinity. It is shown here thatmonoethylamine in the concentration used herein elfectively kills thecatalyst.

Example 3 The procedure of Example 1 is repeated in all respects exceptthat in this case 0.1 millimole of diethyl amine -(C H NH is added. Inthis case there is recovered 2.6 grams of polypropylene of which 87% isinsoluble-in heptane. It is thus shown by comparison with Example 1 thatdiethyl amine substantially reduces the yield of polypropylene.

Example 4 The procedure of Example 1 is repeated in every respect exceptthat 0.1 millimole of triethylamine is added to the reactor after thecatalyst components are charged. In this case there is recovered a totalof 30 grams of polymer, 92% of-which is insoluble in boiling heptane. Itis thus shown that triethylamine is extreme 1y effective in improvingthe crystallinity of polypropylene while at the same time evenincreasing the yield of the polymer.

Example The procedure of Example 1 is repeated in a series of individualruns in which in each case a different trialkyl amine is added to thereactor in the amount of 0.1 millimole after the catalyst components arecharged. The amines added are, respectively, trimethyl amine, triethylamine, tripropyl amine and tributyl amine. Of this series the triethylamine is by far the most effective, resulting in a yield of 30 grams ofpolypropylene having 92% insoluble in boiling heptane, as also shown inExample 4. Next most effective is tripropyl amine, which results in thesame crystallinity but only a 20 gram yield. Next is tributyl amine,which results in 20 gram yield of 84% insoluble. Trimethyl amine isessentially ineffective, resulting in a yield of 7 grams ofpolypropylene having only 79% insoluble in heptane, i.e., about as low acrystallinity as in the absence of amine.

Example 6 The procedure of Example 1 is repeated in four separate runsin which in each case a dialkyl amine is added to the reactor in theamount of 0.1 millimole after the catalyst components are charged. Theamines added are, respectively, dimethyl amine, diethyl amine, dibutylamine and diheptyl amine. The most effective in this group is dibutylamine, which results in a yield of 18.5 grams of polypropylene having acrystallinity of 92% insoluble in heptane. Diheptyl amine results in a10.1 gram yield with 90% insoluble in heptane, Diethyl amine anddimethyl amine result in yields of only 2.7 and 1.1 grams, respectively,having percent insolubles of 87 and 88, respectively, and are thus notvery effective in improving crystallinity while adversely affectingyield.

Example 7 The procedure of Example 1 is repeated except that in severalindividual runs different monoalkyl amines are added to the reactor inthe amount of 0.1 millimole after catalyst components are charged. Theamines are monoethyl amine, monobutyl amine and a branched primary amineof a (C -C alkane. The last named amine results in a yield of 12.5 gramsof polypropylene having 89% insoluble in heptane with n-butyl amineresults in a yield of 26.9 grams having 84% insoluble. Monoethyl amineaffects the yield adversely, as shown in Example 2 above.

Example 8 The procedure of Example 1 is repeated in a series of threeexperiments in which in each instance an unsubstituted nitrocycliccompound having one nitrogen atom per ring is added to the extent of 0.1millimole after the catalyst components are charged. The severalcompound added were piperidine,

pyridine,

and a,a'-dipyridyl,

In each event the yield of polypropylene is nil.

8 Example 9 The procedure of Example 1 is repeated in a series ofexperiments in which in each event 0.1 millimole of an alkyl substitutednitrocyclic compound is added to the reactor after the catalystcomponents are charged. The compounds added are, respectively,a-picoline,

and 2,6-lutidine,

0113 CHa The yields and crystallinites are as follows: u-picolineresults in a yield of 14.9 grams of polypropylene having 93% insolublein heptane; B-picoline results in 0 yield of polypropylene; a-ethylpyridine results in 8.3 gram yield of polypropylene having 88% insolublein heptane; 2,6-lutidine results in 14.7 gram yield of polypropylenehaving 94% insoluble in heptane.

It is thus shown that nitrocyolic compound having one or two methylgroups alpha to the nitrogen atom is a highly effective amine resultingin good yield of polypropylene of high crystallinity. An ethyl groupalpha to the nitrogen results in a somewhat lower yield of somewhatlower crystallinity. Placing the alkyl group in a beta positioncompletely destroys the effectiveness of the amine.

Example 10 In several larger scale runs, 8 liters of isooctane, tomillimoles of AlEt Cl, 28 millimoles of TiCl 5 to 10 millimoles of zincdiethyl and 5 to 10 millimoles of triethylamine were contacted withpropylene at 40 p.s.i.g. In 3 hour runs, 300 to 363 g. of polypropylenecontaining over 93% insolubles and with IV values between 2.7 and 3.2were obtained.

Example 11 The procedure of Example 1 is repeated with the followingdifferences.

The TiCl is added in the form of a slurry of brown TiCl prepared byheating aluminum triethyl and titanium tetrachloride in a molar ratio of1:3 in a hydrocarbon diluent at 80 C. for 3.5 hours, adding sufiicientaluminum diethyl chloride to bring the AlzTi ratio to about 4:1 andheating for one more hour at 80 C. Suflicient slurry is added to provide1 millimole of TiC1 The metal alkyl co-catalyst consists of 4 millimoleof aluminum diethyl chloride, together with specified amounts of zincdiethyl.

The results of several runs are presented in Table 1.

When other zinc dihydrocarbyls, e.g., zinc dimethyl, zinc dii-sopropyl,or zinc diphenyl, are substituted for zinc diethyl in a repetition ofthe above examples, substantially similar trends of conversion andcrystallinity are observed.

Example 13 When it is desired to use other transition metal compounds,e.g., titanium trichloride, vanadium trichloride or zirconiumtrichloride, the procedures of Examples 10 and 11 can be employed andsimilar results obtained. Other aluminum compounds such as the dialkylhalides or trialkyls mentioned above may be substituted for aluminumdiethyl chloride in these examples.

From the foregoing examples and description it will be seen that thepresent invention is capable of numerous modifications, not only inregard to the specific method of preparing and using the catalyst, butalso in regard to the amount of the additives that may be employed.Other modifications such as various polymerization temperatures andpressures, heating cycles, polymer workup and the like may be adopted,but such modifications do not form an essential part of the presentinvention and may be employed without departing from the spirit thereof.

Although zinc di-alkyls are usually added as such, they may also beformed in situ by adding a suitable zinc compound, e.g., zinc fluorideor stearate, which interacts with aluminum alkyl to form zinc alkyl andan aluminum salt.

I claim as my invention:

1. In the process for polymerizing an alpha monoolefin of from 3 to 12carbon atoms per molecule to a solid polymer by contact with catalystcomprising titanium trichloride and an organometallic reducing agent,the improvement which comprises contacting said olefin with a catalystcomposition comprising (a) titanium trichloride,

(b) a zinc dihydrocarbyl having from 1 to 10 carbon atoms in eachhydrocarbyl group, and

(c) from 0.001 mol to 2 mol per mole of zinc dihydrocarbyl of an organicamine selected from the group consisting of heterocyclic nitrogencompounds having fiveto six-membered rings and having an .alkyl radicalsubstituent of up to 6 carbon atoms on at least one carbon alpha to anitrogen atom in the ring.

2. A process according to claim 1 in which said alphamonoolefin ispropylene.

3. A process according to claim 1 in which said zinc dihydrocarbyl iszinc diethyl.

4. A process according to claim 1 in which said titanium trichloride isgamma titanium trichloride.

5. A process according to claim 11 wherein said amine is aliphatictertiary amine having at least carbon atoms per molecule.

6. A process according to claim 11 in which said amine is triethylamine.

7. A process according to claim 11 in which said amine istriisopropylamine.

8. A process according to claim 11 in which said amine isdi-n-butylamine.

9. A process according to claim 1 in which said amine is a-picoline.

10. A process according to claim 1 in which said amine is 2,6-lutidine.

11. -In the process for polymerizing an alpha monoolefin of from 3 to 12carbon atoms per molecule to a solid polymer by contact with catalystcomprising titanium trichloride and an organometallic reducing agent,the improvement which comprises contacting said olefin with a catalystcomposition comprising (a) titanium trichloride,

(b) an aluminum alkyl selected from the group consisting of aluminumtri-alkyls and aluminum dialkyl chlorides,

(c) a zinc dialkyl having from 1 to 10 carbon atoms in each .alkylgroup, and

(d) an organic amine selected from the groups consisting of (1)aliphatic tertiary amines having at least 5 carbon atoms per molecule,(2) aliphatic secondary amines having at least 5 carbon atoms permolecule, (3) aliphatic primary amines having at least 4 carbon atomsper molecule, and (4) hetero cyclic nitrogen compounds having fivetosixmembered rings and having an alkyl radical substituent of up to 6carbon atoms on at least one carbon alpha to a nitrogen atom in thering,

wherein the molar ratio of combined metal alkyls to titanium trichlorideis in the range from 1:1 to 10:1, the molar ratio of zinc diethyl toaluminum diethyl chloride is in the range from 0.001:1 to 0.5 :1, andthe molar ratio of amine to zinc diethyl is in the range from 0.001:1 to20:1.

12. A process according to claim 11 in which said alpha monoolefin ispropylene.

13. In the polymerization of propylene to a solid polymer by contactwith a catalyst comprising titanium trichloride and an organometallicreducing agent, the improvement which comprises contacting propylenewith a catalyst composition consisting of the reaction product of (a)titanium trichloride,

(b) aluminum diethyl chloride,

(0) zinc diethyl, and

(d) an organic amine selected from the group consisting of (1) aliphatictertiary amines having at least 5 carbon atoms per molecule, (2)aliphatic secondary amines having at least 5 carbon atoms per molecule,(3) aliphatic primary amines having at least 4 carbon atoms permolecule, and (4) heterocyclic nitrogen compounds having fivetosixmembered rings and having an alkyl radical substi-tuent of up to 6carbon atoms on at least one carbon alpha to a nitrogen atom in thering,

wherein the molar ratio of combined metal alkyls to titanium trichlorideis in the range from 1:1 to 10:1, the molar ratio of zinc diethyl toaluminum diethyl chlo ride is in the range from 0.001:1 to 0.5: 1, andthe molar ratio of amine to zinc diethyl is in the range from 0.001:1 to20:1.

14. A process according to claim 13 wherein said amine is aliphatictertiary amine having at least 5 carbon atoms per molecule.

15. A process according to claim 13 wherein said amine is triethylamine.

16. A process according to claim 13 wherein said amine is triisopropylamine.

17. In the polymerization of propylene to a solid polymer by contactwith a catalyst comprising titanium trichloride and an organometallicreducing agent, the improvement which comprises contacting propylenewith a catalyst composition consisting of the reaction product of (a)titanium trichloride,

(b) aluminum diethyl chloride,

(0) Zinc diethyl, and

(d) an organic amine selected from the group consisting of heterocyclicnitrogen compounds having fiveto six-mem'bered rings and having an alkylradical 3,027,360 3/1962 Raum 26093.7 substituent of up to 6 carbonatoms on at least one 3,050,471 8/ 1962 Anderson et a1. 26094.9 carbonalpha to a nitrogen atom in the ring, 3,058,963 10/1962 Vandenberg26093.7 wherein the molar ratio of combined metal alkyls to 3,070,54912/1962 Ziegler et al. 26094.9 titanium trichloride is in the range from1:1 to 10:1, 5 3,139,418 6/1964 Marullo et al. 26093.7 the molar ratioof zinc diethyl to aluminum diethyl chloride is in the range from0.001:1 to 0.521, and the molar FOREIGN. PATENTS ratio of amine to zincdie-thyl is in the range from 554,242 2/1957 l 0001 1 to 20:1 559,7271/1958 Belgium.

10 JOSEPH L. SCHOFER, Primary Examiner.

References Cited by the Examiner M. B. KURTZMAN, Assistant Examiner.

UNITED STATES PATENTS 2,905,645 9/1959 Anderson et al 260-94.9 2,971,9252/1961 Winkler et a1. 26093.7

11. IN THE PROCESS FOR POLYMERIZING AN ALPHA MONOOLEFIN OF FROM 3 TO 12CARBONATOMS PER MOLECULE TO A SOLID POLYMER BY CONTACT WITH CATALYSTCOMPRISING TITANIUM TRICHLORIDE AND AN ORGANOMETALLIC REDUCING AGENT,THE IMPROVEMENT WHICH COMPRISES CONTACTING SAID OLEFIN WITH A CATALYSTCOMPOSITION COMPRISING (A) TITANIUM TRICHLORIDE. (B) AN ALUMINUM ALKYLSELECTED FROM THE GROUP CONSISTING OF ALUMINUM TRIALKYLS AND ALUMINUMDIALKYL CHLORIDES, (C) A ZINC DIALKYL HAVING FROM 1 TO 10 CARBON ATOMSIN EACH ALKYL GROUP, AND (D) AN ORGANIC AMINE SELECTED FROM THE GROUPSCONSISTING OF (1) ALIPHATIC TERTIARY AMINES HAVING AT LEAST 5 CARBONATOMS PER MOLECULE, (2) ALIPHATIC SECONDARY AMINES HAVING AT LEAST 5CARBON ATOMS PER MOLECULE, (3) ALIPHATIC PRIMARY AMINES HAVING AT LEAST4 CARBON ATOMS PER MOLECULE, AND (4) HETEROCYCLIC NITROGEN COMPOUNDSHAVING FIVE- TO SIXMEMBERED RINGS AND HAVING AN ALKYL RADICALSUBSTITUENT OF UP TO 6 CARBON ATOMS ON AT LEAST ONE CARBON ALPHA TO ANITROGEN ATOM IN THE RING, WHEREIN THE MOLAR RATIO OF COMBINED METALALKYLS TO TITANIUM TRICHLORIDE IS IN THE RANGE OF 1:1 TO 10:1, THE MOLARRATIO OF ZINC DIETHYL TO ALUMINUM DIETHYL CHLORIDE IS IN THE RANGE FROM0.001:1 TO 5:1, AND THE MOLAR RATIO OF AMINE TO ZINC DIETHYL IS IN THERANGE FROM 0.001:1 TO 2.0:1.